Self-Reported Sleep and Nap Habits and Risk of Mortality in a Large Cohort of Older Women

To determine the association between self-reported sleep and nap habits and mortality in a large cohort of older women. Study of Osteoporotic Fractures prospective cohort study. Four communities within the United States. Eight thousand one hundred one Caucasian women aged 69 and older (mean age 77.0). Sleep and nap habits were assessed using a questionnaire at the fourth clinic visit (1993/94). Deaths during 7 years of follow-up were confirmed with death certificates. Underlying cause of death was assigned according to the International Classification of Diseases, Ninth Revision, Clinical Modification. In multivariate models, women who reported napping daily were 44% more likely to die from any cause (95% confidence interval (CI)=1.23-1.67), 58% more likely to die from cardiovascular causes (95% CI=1.25-2.00), and 59% more likely to die from noncardiovascular noncancer causes (95% CI=1.24-2.03) than women who did not nap daily. This relationship remained significant in relatively healthy women (those who reported no comorbidities). Women who slept 9 to 10 hours per 24 hours were at greater risk of death from cardiovascular and other (noncardiovascular, noncancer) causes than those who reported sleeping 8 to 9 hours. Older women who reported napping daily or sleeping at least 9 hours per 24 hours are at greater risk of death from all causes except cancer. Future research could determine whether specific sleep disorders contribute to these relationships.